In determining the morphemes of a particular language, linguists use, in addition to distributional criteria, also (in varying degrees) criteria of meaning difference. In exact descriptive linguistic work, however, such considerations of meaning can only be used heuristically, as a source of hints, and the determining criteria will always have to be stated in distributional terms […]The chief means whereby such distributional operations can take the place of information about meaning is by taking ever larger environments of the element in question into consideration.
- Harris (1951), a pag.365